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ElCondor
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Location: Vienna, Austria, Europe
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 Posted: Fri Sep 17, 2004 9:10 am Post subject: Multiple NICs init-scripts: link, don't copy! |
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I'm not sure whether to post this here or in "Documentation,Tips an Tricks", but anyway:
The gentoo install guide told me (2 1/2 years ago) that I should simply copy my /etc/init.d/net.eth0 to /etc/init.d/net.eth1 for my second NIC. Well, a certain time after installation and (multiple) upgrades of the system, this won't work anymore, simply because init scripts are subject to change, bringing new features - and I'm rather sure, many admins out there forget to update their copies of the init scripts. IMHO the much better way to do this is linking: | Code: | | ln -s /etc/init.d/net.eth0 /etc/init.d/net.eth1 |
* ElCondor pasa *
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hardcore
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Joined: 01 Nov 2003
Posts: 626
Location: MSU, MI
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| Posted: Fri Sep 17, 2004 10:52 am Post subject: Re: Multiple NICs init-scripts: link, don't copy! |
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| ElCondor wrote: | I'm not sure whether to post this here or in "Documentation,Tips an Tricks", but anyway:
The gentoo install guide told me (2 1/2 years ago) that I should simply copy my /etc/init.d/net.eth0 to /etc/init.d/net.eth1 for my second NIC. Well, a certain time after installation and (multiple) upgrades of the system, this won't work anymore, simply because init scripts are subject to change, bringing new features - and I'm rather sure, many admins out there forget to update their copies of the init scripts. IMHO the much better way to do this is linking: | Code: | | ln -s /etc/init.d/net.eth0 /etc/init.d/net.eth1 |
* ElCondor pasa * |
True that, it's in the newest gentoo handbook, and I believe in the router howto as well.
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nielchiano
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Joined: 11 Nov 2003
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Location: 50N 3E
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| Posted: Fri Sep 17, 2004 12:39 pm Post subject: |
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I would rather Hardlink those files, instead of using symlinks. Won't matter mutch, but it's a bit "cleaner" (no symlinks in the init.d dir)
just omit the -s in the code: | Code: |
ln /etc/init.d/net.eth0 /etc/init.d/net.eth1 |
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fleed
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Joined: 28 Aug 2002
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Location: London
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| Posted: Fri Sep 17, 2004 12:43 pm Post subject: |
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| If you hard link you'll end up with the same situation as if you had copied, I think. |
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nielchiano
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| Posted: Fri Sep 17, 2004 5:23 pm Post subject: |
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| fleed wrote: | | If you hard link you'll end up with the same situation as if you had copied, I think. |
hmm... I don't know if emerge will unlink first, but you might be right... |
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ElCondor
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Location: Vienna, Austria, Europe
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| Posted: Fri Sep 17, 2004 6:59 pm Post subject: |
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| nielchiano wrote: | | fleed wrote: | | If you hard link you'll end up with the same situation as if you had copied, I think. |
hmm... I don't know if emerge will unlink first, but you might be right... |
nope. a hard link is just a second name for a file, exept the difference, that the file will not be deleted until the last hard link / name for it is deleted.
* ElCondor pasa *
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nielchiano
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| Posted: Fri Sep 17, 2004 9:14 pm Post subject: |
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| ElCondor wrote: | | nope. a hard link is just a second name for a file, exept the difference, that the file will not be deleted until the last hard link / name for it is deleted. |
I know what a hardlink is. The point is: if you change one "filename" you also change the other.
The question is: does emerge CHANGE the files, or does he deletes them and creates new ones?
The first case will leave you 2 updated files, while the second one will give you 1 updated file, and a broken link (since they aren't hardlinked anymore) |
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Tsonn
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Joined: 03 Jun 2004
Posts: 550
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| Posted: Fri Sep 17, 2004 11:32 pm Post subject: |
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You don't get broken links with hard links... when a file which is hard linked is removed, the number of remaining references is checked, and the file is only removed if there are none left.
So, in fact, what you might get if the second file is hard linked to the first is the second file being the outdated version, and you're back where you started 
| Code: |
# echo test > file1
# ln file1 file2
# rm file1
# ls
file2
# cat file2
test
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nielchiano
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| Posted: Sat Sep 18, 2004 8:37 am Post subject: |
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| 26199 wrote: | | You don't get broken links with hard links... when a file which is hard linked is removed, the number of remaining references is checked, and the file is only removed if there are none left. |
You don't get my point: from the file-system view there is nothing wrong (as you say). From the user point of view, the hardlink might be broken:
In the case emerge will delete, and copy the new file (instead of changing the one in place) this happens:- emerge deletes file 1
- file 2 isn't toughed and still exists (now without extra names)
- emerge copy's the new file 1
- from the user point of view, his link between 1 and 2 is broken, since 1 is updated and 2 isn't
- Symlinks will not show this problem
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ElCondor
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Location: Vienna, Austria, Europe
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| Posted: Sat Sep 18, 2004 9:11 am Post subject: |
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you're right. even if you move the ._newfile to oldfile, it actually performs a rm on oldfile first so that the hardlink/second name keeps the original file, so hardlinks just work like copies here.
Maybe symlinks are not "clean", but they work for sure
* ElCondor symlinked pasa * 
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